This invention is related to air motors employed for rotating objects, such as a wrench employed to impart a fastening motion to a nut, and more specifically, to an air motor having means responsive to the angular displacement of the rotor for terminating rotation of the nut after it has been rotated through a predetermined angular displacement.
There are many industrial applications which a fastener, such as a nut, must be rotated on a stem to a particular position. For example, the adjusting nut mounted on the valve train of an internal combustion engine is adjusted according to the motion desired of an engine valve. In an automated process, the nut is usually tightened by an air motor having a wrench that engages the nut, then turns the nut to a predetermined tightened position.
One of the conventional practices for terminating rotation of the nut is to provide a torque-responsive means that responds to the elongation of the threaded stem on which the nut is mounted for de-activating the air motor. The location of the nut on the stem depends upon the nut's position when the rotation of the air motor is terminated. The variance between nuts mounted in such an automated process often varies within a range of plus or minus 90.degree. with respect to the desired rotated position.